Acetaldehyde is a very useful chemical compound and is of considerable importance as an intermediate in the production of acetic acid, acetic anhydride, ethyl acetate, acetone, acetal resins and other derivatives.
Acetaldehyde can be produced by a number of chemical processes such as the dehydrogenation of ethanol or the hydration of acetylene. Another route to acetaldehyde is the cobalt catalyzed reaction of methanol with hydrogen and carbon monoxide. However, this method has been plagued with poor selectivity to acetaldehyde. U.S. Pat. No. 4,151,208 discloses improved selectivity to acetaldehyde by including an iodine promoter with the cobalt catalyst in the methanol, hydrogen, carbon monoxide reaction. Although some improvement is shown over the theretofore available processes the selectivity to acetaldehyde was only from 50-60 percent and the methanol conversion only from 50-70 percent.
Other catalyst systems have been employed to catalyze the reaction. For example European patent application Ser. No. 78 30 0607 discloses a process employing an inert liquid and a catalyst of cobalt, iodide or bromide, and arsenic, antimony or bismuth. Japanese Publication No. JA/77/-13611 discloses a process catalyzed by cobalt, a halogen, and phosphorus. Since the reactants, methanol, hydrogen and carbon monoxide are relatively inexpensive and plentiful any process which can facilitate their reaction to acetaldehyde would be very desirable. It would also be highly desirable for the catalyst for this reaction to be a simple and inexpensive as possible. Therefore a process which would improve the conversion and the selectivity of the cobalt-catalyzed, iodide-promoted reaction of methanol, hydrogen and carbon monoxide to selectively produce acetaldehyde would be of great advantage.